Vitamin Deficiency Vitamin Deficiency DisordersDisorders

Abdelaziz ElaminAbdelaziz Elamin

MD, PhD, FRCPCHMD, PhD, FRCPCH

Professor of Child Professor of Child HealthHealth

College of MedicineCollege of Medicine

Sultan Qaboos Sultan Qaboos UniversityUniversity

Muscat, OmanMuscat, Oman

azizminazizmin@hotmail.com@hotmail.com

BACKGROUNDBACKGROUND

Vitamins are organic substances that are essential for several enzymatic functions in human metabolism

Thiamine was discovered in 1912 & was thought to be a vital amine compound & thus the term vitamin was invented

VITAMINSVITAMINS

Vitamins are classified according to solubility into fat soluble & water soluble.

13 vitamins are known, 4 fat soluble (KEDA) & 9 water soluble (C, Folate & the B group).

VITAMIN AVITAMIN A Vitamin A is a generic term for many related compounds.

Retinol (alcohol), Retinal (aldehyde) are often called preformed vitamin A. Retinal can be converted by the body to retinoic acid which is known to affect gene transcription. Body can convert -carotene to retinol, thus called provitamin A.

FUNCTIONSFUNCTIONS

•VisionVision:: integrity of eye & formation of rodopsin necessary for dark adaptation.•Regulation of gene expressionRegulation of gene expression: vital to cell differentiation & physiologic processes

•Growth & developmentGrowth & development

•ImmunityImmunity: important for activation of T lymphocyte, maturation of WBC & integrity of physiological barrier.

Nutrient InteractionsNutrient Interactions

•Zinc deficiency interfere with vitamin A metabolism in several ways:

It decreases the synthesis of retinol binding protein, which transports retinol to tissues.

It decreases the activity of the enzyme retinyl palmitate, which is necessary for release of retinol from the liver.

Zn is needed for the enzyme that convert retinol into retinal.

Nutrient Interactions/2Nutrient Interactions/2•Iron & vitamin A.Iron & vitamin A.

Vitamin A deficiency may exacerbate IDFVitamin A supplementation improves iron status among children & pregnant women.Combining vitamin A with iron controls IDA more quickly & effectively than using iron alone.

VITAMIN A UNITSVITAMIN A UNITS

1 g of retinol = 6 g of -carotene.

3 g of retinol = 10 international units of vitamin A.

100 mg carrots contain 10 mg of -carotene.

Life stageLife stage g/dayg/day

InfantsInfants 400-500400-500

ChildrenChildren 300-600300-600

AdolescentAdolescent 900M- 700F900M- 700F

AdultAdult 900M- 700F900M- 700F

Pregnant womenPregnant women 750-800750-800

Lactating womenLactating women 122-1300122-1300

Recommended AllowanceRecommended Allowance

Animal FoodsAnimal Foods Plant FoodsPlant Foods

Cod liver oilCod liver oil Sweet potatoSweet potato

Liver & kidneyLiver & kidney CarrotsCarrots

EggEgg CantaloupeCantaloupe

ButterButter SpinachSpinach

Milk & cheeseMilk & cheese ApricotApricot

Fish & meetFish & meet PapayaPapaya

RICH DIETARY SOURCESRICH DIETARY SOURCES

Vitamin A deficiencyVitamin A deficiency

•Deficiency of vitamin A leads to:

Night blindness & xerophthalmia

Growth retardation

Acquired immune deficiency

Keritinization of epithelia in RT, GIT & UT with increased risk of RTI, malabsorption & UTI.

THERAPEUTIC USESTHERAPEUTIC USES

Vitamin A deficiency

Boosting immunity of infants

Skin disorders

Acute promyelotic leukemia

Cancer prevention (lung & breast)

TOXICITYTOXICITY

•Vitamin A in excess leads to:Vitamin A in excess leads to:

•Dermatitis with xanthosis cutis

•Hepatosplenomegaly

•Bone pain & increased risk of fracture

•Pseudotumor Cerebri

VITAMIN DVITAMIN D

Vitamin D comprises a group of sterols; the most important of which are cholecalciferol (vitamin D3) & ergosterol (vitamin D2).

Humans & animal utilize only vitamin D3 & they can produce it inside their bodies from cholesterol.

Cholesterol is converted to 7-dehydro-cholesterol (7DC), which is a precursor of vitamin D3.

VITAMIN DVITAMIN D

Exposure to the ultraviolet rays in the Exposure to the ultraviolet rays in the sunlight convert 7DC to cholecalciferol.sunlight convert 7DC to cholecalciferol.

Vitamin D3 is metabolically inactive until it is Vitamin D3 is metabolically inactive until it is hydroxylated in the kidney & the liver to the hydroxylated in the kidney & the liver to the active form 1,25 Dihydroxycholecalciferol.active form 1,25 Dihydroxycholecalciferol.

1,25 DHC acts as a hormone rather than a 1,25 DHC acts as a hormone rather than a vitamin endocrine & paracrine properties.vitamin endocrine & paracrine properties.

FUNCTIONSFUNCTIONS

•Calcium metabolismCalcium metabolism: vitamin D enhances ca absorption in the gut & renal tubules.•Cell differentiationCell differentiation: particularly of collagen & skin epithelium

•ImmunityImmunity: important for Cell Mediated Immunity & coordination of the immune response.

Vitamin D deficiencyVitamin D deficiency

•Deficiency of vitamin D leads to:Deficiency of vitamin D leads to:

Rickets in small children.

Osteomalacia

Osteoporosis

GROUPS AT RISKGROUPS AT RISK

•Infants•Elderly•Dark skinned•Covered women•Kidney failure patients•Patients with chronic liver disease•Fat malabsorption disorders•Genetic types of rickets•Patients on anticonvulsant drugs

Sources of Vitamin DSources of Vitamin D

Sunlight is the most important source

Fish liver oil

Fish & sea food (herring & salmon)

Eggs

Plants do not contain vitamin D3

THERAPEUTIC USESTHERAPEUTIC USES

Rickets & Osteomalacia

Osteoporosis

Psoriasis

Cancer prevention (prostate & colorectal)

Autoimmune diseases

TOXICITYTOXICITY•Hypervitaminosis DHypervitaminosis D

causes hypercalcemia, which manifest as:

Nausea & vomiting

Excessive thirst & polyuria

Severe itching

Joint & muscle pains

Disorientation & coma.

RICKETS